An IP Multimedia service involves the dynamic combination of voice, video, messaging, etc. within the same session. By growing the number of basic applications and the media that it is possible to combine, the number of services offered to the end user will grow exponentially and the inter-personal communication experience will be enriched. This will lead to a new generation of personalized, richer multimedia communication.
A combinational IP Multimedia service is a Multimedia service that includes and combines both a Circuit Switched media (such as voice) and a Packet Switched media over the IP Multimedia Subsystem (IMS) (such as pictures, video, presence, instant messages, etc.). Combinational IP Multimedia enables a user during a Circuit Switched (CS) voice conversation with another user to take a picture, an audio/video clip, etc. and transmit this content to the other party in the conversation. Either party in the conversation may initiate transmission of content to the other party. IMS is the technology as defined by 3 GPP to provide IP Multimedia services. FIG. 1 illustrates a family of combinational services referred to below as weShare, whilst FIG. 2 illustrates the IMS architecture in 3 GPP.
A combinational IP multimedia service requires a protocol to carry the images (or audio/video clip, video, etc) during the CS call. Images/Clips must be transferred using a transport protocol such as TCP, which takes care of retransmissions and ensures that the packets, which the images/clips are broken into, are delivered in order. There also needs to be a user-plane protocol at a higher level (above TCP) that delimits the transfer of an image/clip Message Session Relay Protocol (MSRP) is a candidate for transferring content such as images or video-lips. MSRP is being specified by IETF and is currently described in the document “draft-ieff-simple-message-sessions-08.txt”. MSRP provides a mechanism to transport session-mode contents (e.g. instant messages, pictures, etc.) between endpoints. However, aspects such as weShare service-specific policy enforcement and charging reporting are not covered by the MSRP and by the 3 GPP IMS standards.